Valve-reversing mechanism



(No Model.) K I W'. L. TO'BEY. VALVE REVERS-ING MEGHANISM. No. 359,649.Patented Mar. 22, 1887.

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UNITED STATES PATENT GFFIC' WILLIAM L.l rroBnY, or BosroN,'MAssAcHUsnrra VALVE'=REVERSING NIECHANISIVI.

SPECIFICATION forming part of Letters Patent No. 359.649, dated March22l 1887.

Application tiled July 23, 1886. Serial No. 208.841.

To all whom it may concern:

Beit known that I, WILLIAM L. ToBnY, of Boston, 'county of Suffolk, andState of Massachusetts, have invented an Improvement in Valve-ReversingYMechanisms, of which the following description, in connection with theaccompanying drawings, isaspeciflcation, like letters on the drawingsrepresentinglike parts.

This invention has for its object to provide steam-engines with avalve-motion to take the place of the link-motion now commonly used toreverse the rotation of the crank-shaft.

My valve-motion is an improvement upon the valve-motion known toengineers as the Marshall or Hackworth valve-revers ing gearing, and hasfor its primary object to obtain equal opening and closing of the valveat each end of the stroke of the piston with equal points of cut-0H', myimproved valvegearing being simple in construction and easy ofadjustment. v

My invention consists, essentially, of a valve and valve-stem, andaneccentric-rod, a point in which moves in a path oblique to the length ofthe said eccentric-rod, combined with a lever fulcrumed to the saideccentric-rod, and having one end connected to the valve-stem and itsother end moving in afixed path, substantially as will be hereinafterdescribed.v

Figure 1, in section and elevation, shows a sufficient portion of asteam-engine to enable my invention to be understood; Figs. 2 and 3,diagrams showing different positions occupied by my improvedvalve-gearing to pro- `duce reverse rotations of the crank-shaft, andFigs. 4 and 5 details to be referred to.

The cylinder A, piston a, provided with the usual piston-rod, a, thevalvechest A, and valve a", contained therein and having the valve-roda3, are and may be of common construction, they being herein shown asconstituting part oi' an upright engine.

The valve-chest A', as shown, is provided with the steam-inlet a.13 andthe ports ct* af" and exhaust-ontlets as, the latter being at the endsof the said valve-chest. The lpiston-rod a is joined by aconnecting-rod, b, to a crank, b', on a crank-shaft, b2. The crankshaftbz has mounted on it an eccentric, b3, provided with an eccentric-rod,b4, to which a link, 126, is pivoted at a point intermediate of the endsofthe (No model.)

said eccentric-rod, as at b5, the other end of the link b being pivoted,as at bi, to a reversing-lever, c, pivotally secured, as at c', to a xedportion of the engine, the said lever being adaptedto be turned on itspivot from the position Fig. l to the positions shown in Figs. 2 and 3,to reverse the movement of the valve a2 and thereby the rotation of thecrank-shaft.

The parts thus far enumerated are the same as in the Marshallvalve-reversing gearing, and also' the same as the Hackworth, except inthe latter the point b5 is a block pivoted to the eccentric-rod, thesaid block moving in a slide attached to the reversing-lever c; but inboth the said `contrivances the valvestem is connected by a valverod tothe end of the eccentric-rod.

The Marshall gearing is objectionable, as it gives unequal opening atthe top and bottom of thev cylinder, and in order to secure equalvopenings to the cylinder it has been necessary to double-port thecylinder at one end.

The excessive friction created by the use oi' the slides in theHaekworth gearing renders the said gearing impracticable.

In accordance with my invention, I obviate the objections due to the useof the double ports at one end of the cylinder, as in the Marshallvalve-gearing, and I overcome the excessive friction common to theHackworth gearing by means of a lever, B, which, in accordance with myinvention, is fulcrumed near its center, as at d, to the end, as hereinshown, of the eccentric-rod b.

The lever B has one of its ends, as shown at dx, connected by thevalve-rod d to the valvestem a3, and has its other end suspended, as atd2, to an equalizing-link, d3, pivoted to aiixed portion of the engine;but, instead of pivoting the lever B to the pivoted link Lt-he saidlever may be pivoted in a'block, d5, moving in asta- 'tionary slide, d6.(See Fig. 4.) The equaliz'inglink d gives to the point of the lever Bwhere the latter is connected to the valve-rod substantially equaloscillation above and below the center, thereby securing substantiallyequal opening and closing of the valve at both ends of the stroke of thepiston.

When the reversing-lever c occupies the central position shown in Fig.1, the fulcrum b5 of t-he eccentric-rod b4 moves in a substan- IOCtially horizontal path, as showvn in Fie. 5 hy full linef. \Vith thereversingdever c thrown into the position Fig. 2, the path of movementof the fulerum b5 s indicated bythe dotted 5 1inef,:1nd when thereversing-lever c is thrown in the position shown in Fig. 3 to reversethe movement of the valves, and thereby the romtion ofthe crank-shaft,the path of movement of the fulermn b5 is indicated by the dotted iinef.

It will be noticed that thepnth of movement of the fnlerum If is in :rnoblique direction to the length ofthe eccentric-rod when thereversing-lever c is on either side of its central 15 position.

I einim- In n steam valve-motion, a valve and valvestem, and aneccentric-rod, n point in which moves in a path oblique to the length ofthe said eccentric-rod, combined with a lever fulerumed to the saideccentric-rod, and having one end connected to the Valve-Stem und itsother end moving in a. xed path, substantially as and for the purposeset forth.

In testimony whereofI have signed my name to this specification in thepresence of two subscribing witnesses.

ViLLTAM L. TOBEY.

YVitnesses:

G. W. GREGORY, J. H. CHURoHILL.

